Semi-quantitative (SQX) analysis of Ultra Carry method for SPEX LPC Standard 1
The Ultra Carry preparation method concentrates any aqueous liquid sample on a specially designed absorbent pad that is mounted on a Mylar film, which is stretched across a rigid plastic disk. This unusual sample holder (Figure 1) allows the Rigaku ZSX Primus II WDXRF spectrometer to do a standard water type analysis in only a few minutes and attain values at the ppb level, which rival the competitive ICP analysis method for sensitivity- while offering a reduced preparation time, sample quantity, and waste.
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Figure 1 |
SPEX LPC Standard 1 is an aqueous liquid sample that contains 20 ppm concentrations of a full suite of elemental components, along with a few spiked addition elements at 100 ppm and 5 ppm. 500 microliters of liquid sample was deposited and then dried (60°C for 45 min.) on the Ultra Carry holder. The sample was then run through the "standardless" SQX analysis software on the Rigaku ZSX Primus II Spectrometer under a vacuum atmosphere. The resulting semi-quantitative spectral scan (Figure 2) and results (Chart 1) from the sample are shown below.
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Figure 2 |
|
Element |
SPEX LPC1 |
Rigaku SQX |
Calculated |
|
Na |
20.0 |
18.5 |
76 |
|
P |
100.0 |
90.8 |
56 |
|
K |
100.0 |
116.0 |
12 |
|
V |
100.0 |
18.8 |
34 |
|
Cr |
20.0 |
19.1 |
26 |
|
Mn |
20.0 |
20.6 |
16 |
|
Fe |
20.0 |
19.3 |
18 |
|
Co |
20.0 |
19.7 |
17 |
|
Ni |
20.0 |
20.3 |
20 |
|
Cu |
20.0 |
18.2 |
19 |
|
Zn |
20.0 |
17.8 |
18 |
|
As |
20.0 |
19.2 |
16 |
|
Se |
20.0 |
17.8 |
24 |
|
Sr |
20.0 |
19.0 |
25 |
|
Mo |
20.0 |
18.4 |
27 |
|
Ag |
5.0 |
3.4 |
152 |
|
Cd |
20.0 |
22.3 |
182 |
|
Sn |
20.0 |
22.5 |
40 |
|
Sb |
20.0 |
21.5 |
43 |
|
Ba |
20.0 |
17.5 |
105 |
|
Tl |
20.0 |
20.1 |
81 |
|
Pb |
20.0 |
17.4 |
76 |
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Chart 1: SQX analysis with Ultra Carry. |
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The Lower Limits of Detection (LLD) for this standard are calculated, based on a 100-second count time per element and a power signature of 2.5 kW, and reported in ppb units. As the data states, the sensitivity-increasing Ultra Carry method for analyzing aqueous liquids allows a standard like SPEX LPC 1 to be reported at levels that rival ICP techniques.
